There are patents related to shear wave generation apparatus and method. The U.S. Pat. No. 3,159,232 by D. W. Fair in 1964, the U.S. Pat. No. 4,135,599 by Delbert W. Fair, 1977 and the U.S. Pat. No. 4,388,981 by Delbert W. Fair in 1983 all disclosed a shear wave generator by using pyramidal bodies connected to a horizontal plate to couple the earth surface. The horizontal vibrator is located on top of the plate to generate the shear wave. The U.S. Pat. No. 4,301,888 by James Gibson in 1981 disclosed an impulse shear wave generator using a pair of guillotinized, separately activated hammer/anvil sub-assemblies. The U.S. Pat. No. 4,310,066 by Ihn J. Won in 1982 disclosed a torsional shear wave generator using a hollow elongated shaft having a plurality of circumferentially spaced vanes and a loading arm that secured to the top portion of the shaft and extends perpendicular to the shaft. The U.S. Pat. No. 4,735,280 by Jack H. Cole in 1987 disclosed a shear wave generator by using a truck mounter horizontal vibrator and the telescoping blade to couple the energy into the earth medium. The U.S. Pat. No. 4,709,362 by Hack H. Cole in 1987 disclosed an orbital vibrator. An annular reaction mass is mounted on a crank by means of bearing. The reaction mass orbitally oscillates relative to the axis of the crank shaft without rotation. The U.S. Pat. No. 4,771,858 by Kent J. Goodloe in 1988 disclosed a shear wave generator which isolates the energy generated by shear wave seismic vibrator from their transport vehicles. The U.S. Pat. No. 4,867,096 by Jack H. Cole in 1989 disclosed a shear wave generator consists of a conical lower end tube and a horizontal vibrator. U.S. Pat. No. 4,922,472 by Jack H. Cole in 1990 disclosed an apparatus for inducing elliptically polarized shear wave by using two shear wave vibrators engaged to the earth medium in cross-polarized attitude and driven at sweep rated having variable phase displacement. The U.S. Pat. No. 5,483,026 by Wilfred P. Hasbrouck, etc. in 1996 disclosed a rotary seismic shear wave source utilizing a heavy flywheel positioned for rotation in a vertical plane to generate and store energy which is then transferred to the ground.
More recently, the U.S. Pat. No. 5,610,875 by James E. Gaiser in 1997 disclosed an exploration method by using a compressional-wave source to produce converted shear waves which are subjected to Alford 4-components rotation to align the observation coordinates with the natural coordinates of the principal anisotropic axes of a birefringent formation. The U.S. Pat. No. 6,065,562 by James M. Bird, etc. in 2000 disclosed a seismic vibrator system for imparting compressional and shear wave vibrations into the earth uses an earth contacting base with a vertical post. The U.S. Pat. No. 6,119,804 by Thomas E. Owen in 2000 disclosed a horizontally polarized shear wave vibrator by using a frame with its base plates coupled with the earth by ground screws. The horizontal drivers are located inside the frame. U.S. 7,650,962 B2 by Mark K. Quinn in 2010 disclosed a shear wave generator by an offset mass rotating in a plane perpendicular to the surface of the ground, which impacts an impact member coupled to the ground.
None of the Patents mentioned has disclosed the means to vibrate an expandable confined body inside a media to create shear waves of different directions.